Prototype Update: hacky sound detection

Minor update: the bots can now hear the player’s footsteps. And the player can run.

Sound detection is a bit hacky. Sounds alert every overlapping NPC when they’re playing, and the NPC then checks to see if it’s too far away. That’s not the hacky part - the silly part is that I’m using Godot’s navigation system to simulate propagation around corners.

It actually works.